Install ceph debs and use installed debs

The ceph task installs ceph using the debian
packages now, and all invocations of binaries installed
in {tmpdir}/binary/usr/local/bin/ are replace with
the use of the binaries installed in standard locations
by the debs.

Author:    Sander Pool <sander.pool@inktank.com>
Signed-off-by: Sam Lang <sam.lang@inktank.com>